A conventional display device, such as a TFT-LCD (Thin Film Transistor-Liquid Crystal Display) or an OLED (Organic Light Emitting Diode) display device, generally includes an upper substrate and a lower substrate. The upper substrate and the lower substrate are bonded by a packaging adhesive in a package area. At present, the packaging adhesive is generally formed on the upper or lower substrate by a screen printing technology, and the upper substrate and the lower substrate are correspondingly attached to each other. The display device, especially the OLED display device, requires a good packaging effect. The OLED display device includes an organic layer that is extremely sensitive to moisture and oxygen. If the packaging effect does not meet the requirements, the lifespan of the OLED display device will be reduced. The desired effect cannot be achieved by using the screen printing technology in related art.